In recent years, a secondary battery, which can be charged and discharged, has been widely used as an energy source for wireless mobile devices. In addition, the secondary battery has attracted considerable attention as a power source for electric vehicles (EV) and hybrid electric vehicles (HEV), which have been developed to solve problems, such as air pollution, caused by existing gasoline and diesel vehicles using fossil fuels.
Small-sized mobile devices use one or several battery cells for each device. On the other hand, middle or large-sized devices, such as vehicles, use a middle or large-sized battery pack having a plurality of battery cells electrically connected to one another because high output and large capacity are necessary for the middle or large-sized devices. In order to provide output and capacity required by a predetermined apparatus or device, a plurality of battery cells or battery modules may be connected in series to each other.
In general, a high-capacity/high-output battery pack is configured to have a structure in which a plurality of battery cells or battery modules is loaded on a base plate in a state in which the battery cells or the battery modules are stacked such that the battery cells or the battery modules are adjacent to each other and a pack housing is coupled to the base plate such that the pack housing surrounds the battery cells or battery modules. In this structure, the battery modules may move due to vibration caused in a driving condition of a device in which the battery pack is mounted. In order to prevent such motion of the battery modules, a tension bar is mounted at the upper ends of the battery modules in a direction in which the battery modules are arranged.
In the above structure, however, it is not possible to sufficiently prevent motion of the battery modules in a lateral direction thereof when vibration is generated from the battery pack in a lateral direction thereof. In addition, since an empty space is provided between the pack housing and the battery modules, condensed water generated on the inner surface of the pack housing due to a temperature difference between the inside and the outside of the battery pack may fall to the upper ends of the battery modules with the result that the battery pack may malfunction.